In semiconductor device formation processes, device dies may be bonded to a wafer. Typically, after the bonding of the dies onto the wafer, a molding compound is applied to encapsulate the device dies and the wafer. After the molding compound is applied, a die saw is performed to saw the wafer and the device dies into packages, wherein each of the packages may include one of the device dies and one of the chips in the wafer. The die saw is typically performed using a blade, which cuts through the scribe lines in the wafer.
The wafer molding process during chip on wafer assembly may induce molding compound shrinkage and coefficient of thermal expansion (CTE) mismatch between, for example, a silicon substrate and the molding compound resulting in an unacceptable wafer level warpage. Wafer warpage may cause damage to through substrate vias (TSVs) and low-k dielectrics in the assembly. It is easy to have thin silicon cracks on the molded wafer due to stress induced during the formation process. It is also difficult to perform the die saw on the mixed material structure—that of the substrate and the molding compound.